Every culture seems to have its own phrases
describing the power of heredity – not just for physical traits, but also for
behavioural ones. (Those last three are peculiar to Ireland, I think). This folk
wisdom, accumulated from centuries of observation of human behaviour, seems to
reflect a widespread belief that genetic effects on behaviour and personality
are strong, indeed dominant over effects of upbringing.

Of course, folk wisdom can be wrong. And
old folk sayings may not reflect current thinking – perhaps people’s opinions
on the subject have changed. Indeed, if you were to take academic discourse on
the subject as a barometer of views of the general public, you might think that
many people ascribe no power to nature at all and most or all of it to nurture
instead. Those debates do not remain within the walls of the academy – we see
them played out in social policies on education, early intervention, in the criminal
justice system, in psychiatric practice and other arenas.

So, do those folk sayings accurately
reflect public opinion on the power of nature over nurture? Well, the easiest
way to find out would be to just ask a bunch of people. However, while there
are lots of surveys of people’s attitudes towards genetic testing or screening
(such as here and here), I was unable to find any on more general beliefs about
heredity, especially of psychological or behavioural traits. (If dear readers
know of any, please let me know).

However, there is one area where these
beliefs are directly tested, which is in assisted reproduction, especially
where it involves sperm or egg donors. In many cases, couples can choose sperm
or egg donors on the basis of any number of characteristics, which prominently
include things like intelligence, educational attainment, musical talent, and
general personality traits, in addition to physical characteristics like
height, body-mass index, athleticism, and general health. Clearly, an interest
in the psychological traits of potential donors reflects an underlying belief
in the heritability of such traits.

This was thrown into stark relief by a case from 2016 that received a lot of media attention. A couple had selected a sperm
donor on the basis of a profile in which he claimed to have an IQ of 160, a
bachelor’s degree in neuroscience, a master’s in artificial intelligence and to
be studying for a PhD in neural engineering. They found out later that he was a
college dropout, with a criminal record, having served time in prison for
burglary, and that he had been diagnosed with schizophrenia and narcissistic
personality disorder. (More details of his story emerged later but the
important thing for this discussion is this initial presentation).

This donor’s sperm had been used to father
36 babies. The couple in question had selected him because his high
intelligence and even his scientific interests matched one of the couple. On
learning of his actual profile, they described it as “A dream turned nightmare
in an instant”. They went on to say: “In hindsight, a hitchhiker on the side of the road would
have been a far more responsible option for conceiving a child.”

This story received a lot of media
attention, in newspaper articles, online magazines, and on radio and
television. All of these stories played up the horror of the couple in question
and the outrageousness of the deceit that had been perpetrated on them. What
struck me at the time, though, in almost all of the coverage I saw, was that no
one questioned whether this couple, and others who had children using this
donor’s sperm, were right to be
horrified. It was taken for granted that the traits of the donor would indeed
have a significant impact on the trait’s of the offspring.

None of the commentators argued that mental
illnesses like schizophrenia were really caused by cold parenting, childhood experiences,
or environmental factors. The common wisdom was clearly that mental illness
runs in families and that having a father with schizophrenia greatly increased
the risk of this highly debilitating and often devastating disorder in the
offspring. (And, of course, this is absolutely true).

Similarly, no one claimed that all children
are born with equal intellectual potential, that eventual differences in intelligence
solely reflect differences in education or societal factors, or that IQ tests
only measure how good you are at taking IQ tests. The understanding that
intelligence is real, important, and substantially heritable was so implicit
that it never came up. (And, of course, this is true too, at least that genetic
differences make a major contribution to relative differences in intelligence between
people – though education and other factors affect the absolute levels that any
individual attains).

When talking about these things in the
abstract or in general terms across the population, many people may espouse a
view that weights nurture more heavily than nature. But when the rubber meets
the road, when people are making choices that they feel may directly and
possibly profoundly affect their children, they clearly place a heavy emphasis
on the power of heredity. And most neutral commentators seem to think that view
is so reasonable that it doesn’t even occur to them to comment on it, never
mind question it.

People looking for sperm or egg donors
clearly prefer those with certain traits and without others. Now, you might say
they’re just hedging their bets. If there is an option to choose donors with
traits deemed more desirable, then they might as well, whether they strongly
believe they are heritable or not. If they’re not really heritable, there’s no
harm done. But it goes beyond just exercising that choice – people are willing to payextra for donors with more desirable traits. (I’m not arguing here
that some traits should be seen as more or less desirable – just that the
“consumers” in this scenario see them as such).

Gamete donation is big business. This is
especially true for egg donors, because eggs are much more difficult and
expensive to collect than sperm and there are both far fewer willing donors and
far fewer actual eggs. This is a strangely unregulated market, especially in
the United States. The American Society for Reproductive Medicine has ethical
guidelines that propose a cap on how much women should be paid for their eggs
($10,000), but most fertility agencies operate outside the medical
establishment and many ignore this guideline. The legality of the ASRM’s
position has been challenged by a number of women, given the overall amounts of
money that such agencies can make from clients and the very high value that
some women can demand for their eggs on the open market. (See here for a
personal story of how this kind of interaction can play out).

The willingness of prospective parents to pay for desirable traits indicates both the value attached to such traits as
well as the confidence attached to
the idea that they are really heritable. If people didn’t think a trait like
intelligence was largely heritable, they wouldn’t pay for more intelligent
donors, no matter how much they value the trait. Clearly, they think it is, as
there are agencies specifically marketing educational attainment as one of the
main selling points of the egg donors from whom prospective parents can choose.
Musical and artistic abilities are also much sought after and many descriptors
of donors include all kinds of other personality traits and lifestyle
descriptors that seem to be of interest to clients.

For example, the Egg Donor Program “markets itself as
an exclusive club where selected donors are referred to as “Premier Donor
Angels: beautiful, accomplished, highly educated” (www.eggdonation.com)”.

The Donor Concierge agency promises
intelligent donors, students in or graduates of Ivy League universities, with a
minimum grade point average.

So, if we take donor selection as the ultimate
test-bed of people’s true beliefs on heredity – where they literally put their
money where their mouth is – it certainly seems that the folk sayings referred
to above do accurately reflect beliefs about psychological traits. (At least
among the admittedly non-random set of people who undertake this kind of
assisted reproduction). Beliefs about the heritability of intelligence or of
mental illness are, in fact, well founded and match our current scientific
understanding. Beliefs about other psychological traits probably substantially
overestimate the importance of genetic effects.

One final note: it seems inevitable that
the market in egg and sperm donation will soon incorporate molecular genetic
profiling and trait prediction. The direct to consumer genomics company 23andMe
had a patent granted in 2008 for what they called their “Inheritance
Calculator”, which would enable people to predict traits of offspring from
genotyped parents or donors. The backlash against the idea led the company to
state that they had “no plans to pursue the idea”.

However, another company, GenePeeks, Inc.,
was established precisely for the purpose of molecularly genotyping potential donors, though it is currently only aimed at predicting possible rare diseases
in offspring between clients and donors. It seems a small step to include other
non-medical traits of interest, however, especially if they can be accurately
predicted from polygenic profiles. Currently, things like intelligence cannot
be accurately predicted for an individual, but it may be possible to generate
comparative scores that would influence donor selection. The new company
Genomic Prediction, Inc., aims to use polygenic profiles to predict risk for
complex disorders – the same approach could certainly be used for many
non-medical traits.

Whatever one thinks about the ethics of
this kind of consumer-driven eugenics, it clearly is only going to increase. The
lay understanding of genetics and heredity is thus already a factor in the
market of assisted reproduction and seems likely to grow in importance over the
coming years.

Comments

Post a Comment

Popular posts from this blog

Can molecular memories of our ancestors’
experiences affect our own behaviour and physiology? That idea has certainly
grabbed hold of the public imagination, under the banner of the seemingly
ubiquitous buzzword “epigenetics”. Transgenerational epigenetic inheritance is
the idea that a person’s experiences can somehow mark their genomes in ways
that are passed on to their children and grandchildren. Those marks on the
genome are then thought to influence gene expression and affect the behaviour
and physiology of people who inherit them. The way this notion is referred to – both in
popular pieces and in the scientific literature – you’d be forgiven for
thinking it is an established fact in humans, based on mountains of consistent,
compelling evidence. In fact, the opposite is true – it is based on the
flimsiest of evidence from a very small number of studies with very small
sample sizes and serious methodological flaws. [Note that there is, by contrast,
very good evidence for this kind…

I recently wrote a blogpost examining the
supposed evidence for transgenerational epigenetic inheritance (TGEI) in
humans. This focused specifically on a set of studies commonly cited as
convincingly demonstrating the phenomenon whereby the experiences of one
generation can have effects that are transmitted, through non-genetic means, to
their offspring, and, more importantly, even to their grandchildren. Having
examined what I considered to be the most prominent papers making these claims,
I concluded that they do not in fact provide any evidence supporting that idea,
as they are riddled with fatal methodological flaws. While the scope of that piece was limited
to studies in humans, I have also previously considered animal studies making
similar claims, which suffer from similar methodological flaws (here and here).
My overall conclusion is that there is effectively no evidence for TGEI in
humans (contrary to widespread belief) and very little in mammals more
generally (with one very…

GWAS (genome-wide association studies) for
psychiatric illnesses may be about to become a victim of their own success. The
idea behind these studies is that common genetic variation – ancient mutations
that segregate in the population – may partly underlie the high heritability of
common psychiatric and neurological disorders, such as schizophrenia, autism,
epilepsy, ADHD, depression, and so on. The accumulating evidence from over ten
years of GWAS strongly supports that idea, with many hundreds of such risk
variants now having been identified. The problem is it’s not at all clear what
to do with that information. GWAS are a method to carry out a kind of
genetic epidemiology, based on a simple premise – if a particular genetic
variant at some position in the genome (say an “A” base, as opposed to a “T” at position 236,456 on chromosome 9) – is associated with an increased risk
of some condition, then the frequency of the “A” version should be higher in
people with the condition than pe…